Select seams easy and fast way?
Yes, but working with such a high-poly mesh isn't advisable for a number of reasons.

Instead, consider using a Subsurf modifier. This allows you to work on the mesh in a low-poly state while still getting the nice smooth curves offered by a high-poly mesh:



That said, if you can manage to select one edge with a seam, then you can press &#8679; ShiftG > Seam to select all other seam edges. &#8679; ShiftB for Border Zoom and, if needed, a reduced minimum viewport clipping distance can help immensely with such a task: